Since most mainframe computers are text-oriented, mainframe computer operators have communicated information (i.e. data and commands) to and from the mainframe computer through relatively unsophisticated cathode ray tube ("CRT") terminals. Such CRT terminals are connected either directly to the mainframe computer, or are connected remotely through a telephonic or other data transmission link. Through these "dumb" terminals, operators commonly send commands and other arguments to the mainframe through a command line displayed on the terminal. In most mainframe computer environments, more than one of these unsophisticated terminals can be connected for communication to the mainframe.
This form of communication between a mainframe computer and its operators suffers from a number of disadvantages. Primarily, due to the limited capabilities of the terminal (i.e. low resolution) and slow rate of information transmission, information received from the mainframe and displayed on the dumb terminal often appears in a cryptic format. Although certain software packages, such as Microsoft Corporation's Windows 3.0, include some rudimentary graphics, only characters and numerics are communicated to the program work area while the graphics appear as periphery.
The mainframe computer also dictates the format and type of information communicated to the operator. Thus, this type of user interface is not very "user friendly". Nor, due to the lack of software and hardware provided on the terminal, does the user have the option of customizing the user interface (i.e. the appearance of the display screen) to a visually or otherwise desirable format.
Moreover, in such a computer system, each mainframe computer and its associated CRT terminals are stand-alone entities. As such, the user interface of one mainframe computer can differ markedly from that of another mainframe computer. This results in a multiplicity of differing computer environments, each for a separate mainframe computer. As a consequence, a computer operator must learn multiple user interfaces in order to be proficient on various mainframe computers running different software packages. What is lacking is a generic or universal interface that can be used with many different mainframe computers.
A universal interface would allow an operator to communicate with a host of mainframe computers, each running separate programs, without having to use or learn a separate user interface for each computer. Additionally, a universal user interface will allow the operator to customize the graphical appearance of data received at his or her display.
With a universal computer interface, the prior dumb CRT terminals can be replaced by personal computers running interface software or using a hardware interface card. By employing a personal computer, the operator can benefit from the software and hardware included in such a device to make the user interface more user friendly. In addition, the operator can combine communication to and from a mainframe computer with other hardware or software applications accessible on the personal computer. Such a universal interface would also increase the power and performance of the personal computer by allowing easy access to a remote mainframe computer.